1. Field of the Invention
The instant disclosure relates to an illumination device, and more particularly, to a light-guide type illumination device.
2. Description of Related Art
With the rapid development of economy, energy consumption by humans is also gradually increasing. As a result, energy-saving electronic devices are gaining widespread popularity. For example, in lighting applications, conventional incandescent light bulbs and fluorescent lamps are gradually phased out by energy-saving light bulbs, which have longer service life, excellent efficiency, and better luminosity.
Although conventional incandescent light bulbs are replaceable by energy-saving light bulbs, the known energy-saving light bulbs use mercury to generate ultraviolet (UV) light for exciting fluorescent coating on the bulbs in producing visible light. Under increasing environmental awareness, the use of mercury-containing energy-saving light bulbs will soon be completely prohibited. Moreover, one type of often seen LED light bulb has restricted illuminating angle and produces significant glare. As a consequence, the mounting of the aforementioned LED light bulbs would vary from the conventional light bulbs, and the user is more susceptible to discomfort due to the glare. In summary, the illumination patterns of the LED light bulbs are generally different from the conventional light bulbs. Therefore, direct replacements of the conventional light bulbs by the LED light bulbs are yet applicable. In some instances, the entirety of the lighting fixture has to be replaced along with the conventional light bulbs to make use the LED light bulbs. The change of the lighting fixtures is neither cost-effective nor encourage the use of LED lightings.